(a) Field of the Invention
This invention relates to an improved method for preparing 5-(pyridinyl)nicotinonitriles.
The Lesher and Opalka U.S. Pat. No. 4,004,012, issued Jan. 18, 1977, shows two methods of preparing 1,2-dihydro-2-oxo-5-(pyridinyl)nicotinonitriles and conversion by hydrolysis to the corresponding nicotinamides and, in turn, the conversion of the nicotinamides to the corresponding 3-amino compounds. These methods are presented structurally in columns 3 and 4 of U.S. Pat. No. 4,004,012. Note in particular the two methods for preparing 1,2-dihydro-2-oxo-5-(pyridinyl)-nicotinonitriles (III in patent), i.e., (1) by reacting .alpha.-(pyridinyl)-.beta.-(R.sub.1 R.sub.2 N)acrolein with .alpha.-cyanoacetamide in the presence of a basic condensing agent, preferably an alkali lower-alkoxide, e.g., sodium methoxide or sodium ethoxide, in a lower-alkanol, e.g., methanol or ethanol; and, (2) by heating .alpha.-(pyridinyl)malonaldehyde with .alpha.-cyanoacetamide in the presence of a catalytic condensing agent, preferably morpholine or piperidine and/or its acetate. As shown in Example A-1 in the paragraph common to columns 9 and 10 of U.S. Pat. No. 4,004,012, the product in method (1) is collected as its sodium salt, recrystallized and then coverted by treatment with hydrochloric acid to 1,2-dihydro-2-oxo-5-(pyridinyl)nicotinonitrile.
A recently published abstract ["Current Abstracts of Chemistry", Vol. 74, Issue 814, Item 285573, 1979] of a Polish publication [Nantkanomirski and Kaczmarek, Polish J. Pharmacol. Pharmacy 30(5), 707-12 (1978)] shows, inter alia, the reaction of 3-dimethylamino-2-(4-pyridinyl)acrolein [same as .alpha.-(4-pyridinyl)-.beta.-(dimethylamino)acrolein] with malononitrile in the presence of sodium methoxide in methanol to poduce 2-methoxy-5-(4-pyridinyl)nicotinonitrile.